There are currently various types of mechanical stress measurement sensors on the market. Thus the applicant also holds Spanish Patent No. 200102474 (publication no. ES2187298) involving a “Perfected sensor for measuring mechanical stress in cables,” which, in general terms, consists of a body with an extensiometric cell and three support points through which the cable passes through tightly, pressing on the cell. Furthermore, the applicant is also the holder of Patent of Addition no. 200402269 (publication no. ES2285879), which patented improvements to the previous patent, with the support points to which the cable is attached being retractable to make it easier to insert the cable.
This invention arose from the need to solve the problem presented by these sensors, in which the width of the cable being measured needs to be calibrated, because when the cable is inserted on the cell, the cable puts initial pressure on the cell as a result of it being inserted. This pressure varies depending on the cable's thickness, since the amount of force needed to insert a 10 mm cable is not the same as for a 0.5 mm cable.
Therefore for example, when using these types of sensors to measure the various cables in a lifting device, operators have the inconvenience of having to continuously modify the data for the cell each time they measure a cable in order to establish its calibre as the new “zero” for measuring with the cable under stress.
Moreover, it should also be noted that the applicant is unaware of the existence of any other type of sensor for measuring mechanical stress in cables that has similar technical, structural and constituent characteristics to the sensor being proposed here, the characteristic details of which are duly summarised in the final claims included with the present description.